High accuracy structured light profiler

Abstract

An optical gauging system for evaluating the surface shape of a workpiece along a particular cross section. The gauging system includes an illumination system which projects a line of light onto the workpiece surface. A viewing system is focused along a line which is illuminated when a workpiece surface is intersected by the line of light. The focused line of the viewing system is imaged onto a linear detector array. A translation mechanism is provided which moves the line of light and the focused line of the viewing system into the workpiece along the plane of the cross section of interest. The relationship between the translation mechanism and the output of the array is related to the profile shape of the workpiece along the cross section of interest.

What is claimed is: 
     
       1. An optical system for evaluating the surface shape of a workpiece along a cross section comprising: illumination means for projecting a line or light onto said workpiece,   viewing means for imaging the intersection of said line of light and said workpiece surface onto a linear detector having a plurality of light sensitive regions when some portion of said workpiece surface is at a preselected range distance relative to said illumination means, each of said light sensitive regions being illuminated with light from portions of said line of light corresponding to each of said light sensitive regions only when said portion of said workpiece surface is intersected by said corresponding portion of said line of light at said preselected range distance, said light sensitive regions not being illuminated when said workpiece surface portion is outside said preselected range distance,   translation means for moving said line of light and the focus of said viewing means with respect to said workpiece along said cross section, and   signal processing means for receiving a signal from said detector related to said regions of said detector which are illuminated and for recording said signals at a plurality of different positions of said translation means whereby the relationship between said signals and said translation means position characterizes said surface shape.   
     
     
       2. An optical system according to claim 1 wherein said detector comprises an array including number of light sensitive elements oriented along a line and wherein said signal is related to the number and position of said elements which are illuminated. 
     
     
       3. An optical system according to claim 1 wherein said detector comprises a number of light sensitive elements and said signal processing means determines the central position of said elements which are illuminated. 
     
     
       4. An optical system according to claim 1 wherein said illumination means comprises a laser light source. 
     
     
       5. An optical system according to claim 4 wherein said laser is pulsed to thereby freeze relative motion between said laser source and said workpiece. 
     
     
       6. An optical system according to claim 1 wherein said illumination means comprises a light source and lens means, and wherein said illumination means is carried by a movable portion of said translation means. 
     
     
       7. An optical system according to claim 1 wherein said viewing means is fixedly mounted to a movable portion of said translation means. 
     
     
       8. An optical system according to claim 1 wherein said illumination means comprises a light source and lens means fixedly mounted, and first optical means having portions mounted to a movable portion of said translation means for translating said line of light along said cross section and wherein said detector is fixedly mounted and said viewing means includes second optical means mounted to said movable portion of said translation means for maintaining said focus of said viewing means at said intersection. 
     
     
       9. An optical system according to claim 8 wherein said first optical means comprises a pair of right angle reflective surfaces and a follower mirror which is movable with respect to said translation means movable portion. 
     
     
       10. An optical system according to claim 1 wherein a movable portion of said translation means supports a first and second pentaprism and wherein a light source of said illumination means and said detector are fixedly mounted with respect to said translation means, said first pentaprism directing said line of light toward said workpiece and said second pentaprism directing said intersection line to said detector, and wherein said translation means movable portion moves along an axis inclined to the plane of said cross section at 45 degrees. 
     
     
       11. An optical system according to claim 1 wherein said linear detector comprises a scanning detector.